Improve test coverage report on Azure Pipelines (#49)

The reports are rendered without CSS on Azure Pipelines, see this issue: [microsoft/azure-pipelines-tasks#3027](microsoft/azure-pipelines-tasks#3027). 
There are workaround, but I reckon it's not worth adding further dependencies for the project to solve this.

Author: pviotti

azure-pipelines.yml

@@ -33,4 +33,6 @@ steps:
 
 - task: PublishCodeCoverageResults@1
   inputs:
-    summaryFileLocation: $(System.DefaultWorkingDirectory)/**/clover.xml
+    codeCoverageTool: Cobertura
+    summaryFileLocation: '$(System.DefaultWorkingDirectory)/coverage/cobertura-coverage.xml'
+    reportDirectory: '$(System.DefaultWorkingDirectory)/coverage/lcov-report'

jestconfig.json

@@ -18,5 +18,14 @@
     "dist-esm"
   ],
   "testResultsProcessor": "./node_modules/jest-junit-reporter",
-  "collectCoverage": true
+  "collectCoverage": true,
+  "coveragePathIgnorePatterns": [
+    "/node_modules/",
+    "/test/"
+  ],
+  "coverageReporters": [
+    "cobertura",
+    "lcov",
+    "text"
+  ]
 }